Black holes are something that are usually extremely difficult to study in any detail from far away, so scientists in Italy have done the next best thing— creating microscopic imitation black holes in the lab. Using nothing more than lasers, a sample of pure glass, and sensitive detectors they have created a miniature environment that mimics the conditions of a black hole.
What the Italian physicists have made with their laser disturbance moving through glass is a tiny zone where (at least amid the disturbance itself) light cannot move forward, which is just the situation at the event horizon of a black hole.
From the perspective of the RIP — consider, for the moment, the disturbance zipping through the glass to be a sort of physical thing all by itself — the contention between the light and the local perturbation in the glass causes the light to come to a standstill. This is just what happens at the event horizon of a black hole.
In one case the progress of light is frustrated by the immense warping of space by gravity, in the other the progress of light is frustrated by the warping of the optical environment in the glass.
What happens in the glass is what happens in the black hole: the vacuum will sprout virtual particle pairs, in this case pairs of parcels of light, or photons. However, in the high-energy environment of the artificial event-horizon, some of the virtual photons will be converted into real photons.
And indeed the INFN scientists see light coming out of their glass sample. But is this truly Hawking radiation made in the wrenching pulse within the laser disturbance, in analogy to light emitted from black holes, or could it be coming from somewhere else?
The leader of the Italian team of researchers, Daniele Faccio, who works at Insubria University in Como, Italy (where the research was done), said that all other known origins of the light can be ruled out. The careful tuning of the laser pulse precludes the light having been absorbed by the atoms in the crystal sample, he said. The use of an oriented laser pulse also rules out the idea that the Hawking radiation observed to the side of the glass could be light scattered from the laser beam.